In automotive vehicles today, there are two main types of low voltage (i.e., 6 to 24 volt) fuses in use. The first and older type of low voltage automotive fuse is the glass ferrule fuse, which is also called a cartridge-type fuse, and has a hollow glass body. Like almost all fuses, it contains a small filament or fuse link that is designed to melt and interrupt the circuit if too much current passes through the fuse. The second and newer type of low voltage automotive fuse called an automotive blade-type fuse, which also includes a fuse link and which is further described below. FIG. 1 of the drawings shows an exemplary fuse box which contains both types of fuses, as well as two preferred sizes of the fuse adapter of the present invention.
The ferrule fuse is designed to fit within a ferrule fuse socket. Each automotive vehicle has at least one fuse box and each has numerous fuses and sockets as illustrated in FIG. 1. The ferrule fuse socket, in particular, is usually a rectangular recess which most often comes in two relatively standard sizes, the first or large size being approximately 13/8 inch (in.) by 3/8 in., and the second or smaller size being approximately 7/8 in. by 3/8 in. by 154 in. Each standard size socket is typically provided with a pair of spring-steel retaining clips designed to removably accept and make electrical contact with the metallic end caps of a standard size glass-type ferrule fuse.
The Society of Automotive Engineers ("SAE") Standard No. J554b lists the following five sizes as standard lengths for the glass ferrule (i.e., cartridge type) fuse: 1.25 inch, 1.062 inch, 0.875 inch, 0.75 inch, and 0.625 inch. Each of these sizes has the same basic diameter, which is in a range from 0.247 to 0.253 inch, i.e., about one-quarter inch. In practice, I have observed that the two most commonly used length fuses appear to be the 1.062 inch length fuse and the 0.75 inch length fuse. An estimated one-half of the 100 million cars and trucks on the road today in this country utilize glass ferrule fuses to protect their electrical systems.
Generally speaking, anyone who has attempted to change a glass ferrule fuse has had a difficult experience. These fuses are difficult to access for several reasons. The fuse box itself may be in a location difficult to reach, especially in older cars. In most fuse boxes, the fuses are recessed and difficult to grasp using just the hand. Glass is fragile by nature, and a glass ferrule fuses tends to break when incorrectly pried from its socket. A common solution to the problem is the use of a special tool which can clamp onto the body of the fuse. Insertion and extraction is obviously facilitated by use of this special tool. However, many car owners do not own this tool, or if they do, they do not carry it in their vehicles, which makes it unavailable if they should need it while on the road. Other common problems include complaints that the ferrule fuses are not well labeled and that their labels are difficult to read. I have found that some automotive parts stores are discontinuing or are in short supply of the glass ferrule fuses, even in the commonly used amp ratings. So, as a practical matter, the cars that use the older type fuses may outlast the production or at least the ready supply of the ferrule automotive fuse.
The above problems have necessitated the design of the newer blade-type fuse, which is described in SAE Standard J1284. The automotive blade-type fuse is universal, in that it comes in one standard physical size for the various amp ratings. The amp rating is printed in bold, easy-to-read letters on the plastic body of the fuse. The blade-type fuse is generally rectangular in shape, having a plastic body and two metal flat prongs or blades protruding from the body and providing the electrical pathway to the fuse filament located with the body of the fuse. The blades are coplanar. Each blade generally extends outwardly from the fuse body by about 1/4 inch, is about 3/16 in. wide, and slightly less than 1/32 in. thick. The standard blade-type fuse has 3/16 in. space between the two prongs. An illustrative blade-type fuse is illustrated in the bottom left-hand corner of FIG. 1. Most modern cars have fuse boxes designed to accept these standard blade fuses. The advantages of these newer fuses are that they are easier to replace, are more readily available, and are generally less expensive.
Until the present invention, persons driving older model cars were susceptible to the short supply and rising price of the older glass-type fuse. Accordingly, it is the object of the present invention to provide a fuse adapter that will allow the use of a newer blade-type fuse in an older ferrule fuse socket. It is a further object of this invention to provide an inexpensive and easy means to upgrade the fuse type used in the electrical systems in older model cars.
It is a further object of this invention to provide blade-to-ferrule fuse adapters for use with both the long and short ferrule fuse sockets. It is a further object of this invention to provide owners of older model cars with devices so that they can protect their electrical system using blade-type fuses without the necessity of replacing the entire fuse box assembly.